jackd 1.9.10 coredumpctl and gdb output (with debugging symbols):

           PID: 18408 (jackd)
           UID: 1000 (USER_NAME)
           GID: 1000 (USER_NAME)
        Signal: 6 (ABRT)
     Timestamp: Sat 2015-02-28 11:07:07 PST (1min 34s ago)
  Command Line: /usr/bin/jackd -T -ndefault -dalsa -dhw:0 -r48000 -p1024 -n2
    Executable: /usr/bin/jackd
 Control Group: /user.slice/user-1000.slice/session-c1.scope
          Unit: session-c1.scope
         Slice: user-1000.slice
       Session: c1
     Owner UID: 1000 (USER_NAME)
       Boot ID: fd80b330164645078c79ed36691036de
    Machine ID: MACHINE_ID
      Hostname: iasE
      Coredump: /var/lib/systemd/coredump/core.jackd.1000.fd80b330164645078c79ed36691036de.18408.1425150427000000.lz4
       Message: Process 18408 (jackd) of user 1000 dumped core.

GNU gdb (GDB) 7.9

--- snip ---

Reading symbols from /usr/bin/jackd...done.
[New LWP 18414]
[New LWP 18408]
[New LWP 18413]
[New LWP 18412]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/usr/lib/libthread_db.so.1".
Core was generated by `/usr/bin/jackd -T -ndefault -dalsa -dhw:0 -r48000 -p1024 -n2'.
Program terminated with signal SIGABRT, Aborted.
#0  0x00007fece31164b7 in raise () from /usr/lib/libc.so.6
(gdb) where
#0  0x00007fece31164b7 in raise () from /usr/lib/libc.so.6
#1  0x00007fece311788a in abort () from /usr/lib/libc.so.6
#2  0x00007fece3945fcd in __gnu_cxx::__verbose_terminate_handler() () from /usr/lib/libstdc++.so.6
#3  0x00007fece3943e56 in __cxxabiv1::__terminate(void (*)()) () from /usr/lib/libstdc++.so.6
#4  0x00007fece3943ea1 in std::terminate() () from /usr/lib/libstdc++.so.6
#5  0x00007fece3944106 in __cxa_rethrow () from /usr/lib/libstdc++.so.6
#6  0x00007fece3c63103 in ClientKill (refnum=<optimized out>, this=<optimized out>)
    at /home/USER_NAME/pkgbuilds/jack2/src/jack-1.9.10/common/JackLockedEngine.h:168
#7  Jack::JackSocketServerChannel::ClientKill (this=this@entry=0x7fece17fe048, fd=fd@entry=11) at ../posix/JackSocketServerChannel.cpp:177
#8  0x00007fece3c6322c in Jack::JackSocketServerChannel::Execute (this=0x7fece17fe048) at ../posix/JackSocketServerChannel.cpp:243
#9  0x00007fece3c40200 in Jack::JackPosixThread::ThreadHandler (arg=0x7fece17fe160) at ../posix/JackPosixThread.cpp:59
#10 0x00007fece2ecd374 in start_thread () from /usr/lib/libpthread.so.0
#11 0x00007fece31cb27d in clone () from /usr/lib/libc.so.6